@matheusbsbs / matheus-bagliano / commits / ceb96a160b

midx: fix segfault with no packs and invalid preferred pack

When asked to write a multi-pack-index the user can specify a preferred pack that is used as a tie breaker when multiple packs contain the same objects. When this packfile cannot be found, we just pick the first pack that is getting tracked by the newly written multi-pack-index as a fallback. Picking the fallback can fail in the case where we're asked to write a multi-pack-index with no packfiles at all: picking the fallback value will cause a segfault as we blindly index into the array of packfiles, which would be empty. Fix this bug by resetting the preferred packfile index to `-1` before searching for the preferred pack. This fixes the segfault as we already check for whether the index is `> - 1`. If it is not, we simply don't pick a preferred packfile at all. Helped-by: Taylor Blau <me@ttaylorr.com> Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Patrick Steinhardt committed Apr 14, 2023 at 08:01 UTC ceb96a160b05c3ec45c416851bac00b711418839

2 files changed +15 -3

midx.c

+3 -3

@@ -1326,17 +1326,17 @@ static int write_midx_internal(const char *object_dir,

1326 }

1327

1328 if (preferred_pack_name) {

1329 - int found = 0;

1329 + ctx.preferred_pack_idx = -1;

1330 +

1331 for (i = 0; i < ctx.nr; i++) {

1332 if (!cmp_idx_or_pack_name(preferred_pack_name,

1333 ctx.info[i].pack_name)) {

1334 ctx.preferred_pack_idx = i;

1334 - found = 1;

1335 break;

1336 }

1337 }

1338

1339 - if (!found)

1339 + if (ctx.preferred_pack_idx == -1)

1340 warning(_("unknown preferred pack: '%s'"),

1341 preferred_pack_name);

1342 } else if (ctx.nr &&

t/t5319-multi-pack-index.sh

+12

@@ -183,6 +183,18 @@ test_expect_success 'write midx with --stdin-packs' '

183

184 compare_results_with_midx "mixed mode (one pack + extra)"

185

186 +test_expect_success 'write with no objects and preferred pack' '

187 + test_when_finished "rm -rf empty" &&

188 + git init empty &&

189 + test_must_fail git -C empty multi-pack-index write \

190 + --stdin-packs --preferred-pack=does-not-exist </dev/null 2>err &&

191 + cat >expect <<-EOF &&

192 + warning: unknown preferred pack: ${SQ}does-not-exist${SQ}

193 + error: no pack files to index.

194 + EOF

195 + test_cmp expect err

196 +'

197 +

198 test_expect_success 'write progress off for redirected stderr' '

199 git multi-pack-index --object-dir=$objdir write 2>err &&

200 test_line_count = 0 err